Many of the computers systems available today have a general structure which includes a central processing unit (CPU) which is coupled to a memory, a display device, a keyboard and a position locator via respective buses. A user manipulates the keyboard or the position locator to generate signals representing commands which are sent to the CPU across the respective bus. The position locator generates signals which indicate a position on a display screen of the display device; often the position corresponds to the location of a cursor which is displayed on the display screen. However, with touch sensitive display devices, the position may correspond to the location of the display device that is touched. Commonly used position locators include mouse devices, trackball devices, thumbwheels, tablets, scanline sensitive stili, touch or proximity sensitive display screens, joysticks, and radio-frequency digitizing devices. The term position locator is intended to include any device which indicates a position on a display screen. The CPU sends signals to the display device to cause the display device to display information, either in the form of text or in the form of graphical representations. The CPU retrieves instructions from the memory and executes the instructions to perform tasks. A group of instructions is collectively called a computer program. During execution by the CPU, the instructions are collectively called a computer process.
Information is displayed on the display screen as symbols, each symbol including icons, text, or both. Examples of symbols which are displayed on the display screen include a menu bar, icons, text and a time display. Each of these symbols represent various pieces of information or functionality. Each symbol has a number of visual characteristics. For example, an icon has a color and a shape and text has a font, a font size and a color. Similarly, a time display has a font, a size, a color, and a time display format, e.g., a 24-hour or a 12-hour clock.
There are two commonly used methods altering visual characteristics of a given symbol which is displayed on a display screen. With both of these methods, the given symbol must first be identified by the user. An example of a way in which a user identifies a symbol displayed on the display screen is by positioning a cursor over the symbol by appropriate manipulation of the position locator and actuating the position locator. For example, a mouse device is typically actuated by pressing a button on the mouse device.
In the first method for altering the visual characteristics of a symbol, the cursor is used to access a pull-down menu from the menu bar to provide a variety of characteristic options. The cursor is then positioned over a given characteristic option and the given characteristic option is highlighted. The user then actuates the position locator to cause the CPU to execute instructions which change the characteristic of the selected symbol to the characteristic indicated by the highlighted characteristic option. For example, referring to FIG. 1, the font characteristic of a selected text symbol may be altered by selecting font pull-down menu 102 from a menu bar, selecting a particular font characteristic, e.g., a Times font, from the pull-down menu as indicated by cursor 104 and actuating the position locator to select the particular font characteristic.
In the second method for altering a visual characteristic, a characteristic window in which information describing various characteristics is accessed and displayed. This characteristic window includes displays of various characteristic control devices such as buttons or types of selectors. By appropriate manipulation of the characteristic control devices, a user can alter the characteristics of a selected symbol. For example, referring to FIG. 2, the polygon characteristics of a selected symbol may be altered by accessing polygon attribute window 202, selecting a particular polygon characteristic (e.g., a open versus a closed polygon) from the window as indicated by a cursor and actuating the position locator to select the particular polygon characteristic.
An enhancement to this second method is exemplified by certain characteristic manipulation features which are present in the OS/2.RTM. operating system available from IBM Corporation of Armonk, N.Y. In the OS/2 operating system, a user can alter a characteristic of a graphical feature by a method known as dragging and dropping. The term "graphical feature", as used herein, is a graphical item or representation on a display device. Examples of graphical features include title bars of windows, a menu bar, icons, window backgrounds and the screen background. In such computer systems, a characteristic, such as a color, of a graphical feature is selected from a display of several possible values of the characteristic. The selected value is dragged and dropped onto the graphical feature to set the characteristic to that value. For example, in the OS/2.RTM. operating system, a color is selected by a user from a palette which is displayed on the display screen. The user then drags and drops the selected color onto the background, thus setting the color of the background to the selected color.